Light emitting diodes and laser diodes are well known solid state electronic devices capable of generating light upon application of a sufficient voltage. Light emitting diodes and laser diodes may be generally referred to as light emitting devices (“LEDs”). Light emitting devices generally include a p-n junction formed in an epitaxial layer grown on a substrate such as sapphire, silicon, silicon carbide, gallium arsenide and the like. The wavelength distribution of the light generated by the LED generally depends on the material from which the p-n junction is fabricated and the structure of the thin epitaxial layers that make up the active light emitting region of the device.
Typically, an LED chip includes a substrate, an N-type epitaxial region formed on the substrate and a P-type epitaxial region formed on the N-type epitaxial region (or vice-versa). In order to facilitate the application of a voltage to the device, an anode ohmic contact is formed on a P-type region of the device (typically, an exposed P-type epitaxial layer) and a cathode ohmic contact is formed on an N-type region of the device (such as the substrate or an exposed N-type epitaxial layer). The ohmic contact may typically include an ohmic metal layer, such as platinum, palladium, nickel, titanium, gold, tin or combinations thereof. The ohmic metal layer is generally provided to reduce the forward or turn-on voltage of the device.